In today’s world there are so many
different types of receptacles to choose from—straight
blade, locking-type, and pin and sleeve. The variety of
straight blade receptacles offered by manufacturers alone is
staggering—in fact, wiring device manufacturers produce and
market more than a 1,000 different types. Differences include
electrical rating, color, style, sizes, and configuration.
Receptacles are marketed using terms such as general grade, specification grade, heavy duty, industrial
grade, commercial grade, residential grade,
hospital grade, specialty grade, and fed spec.
There are, however, only four receptacle identities that are
specified in the Standard for Attachment Plugs and
Receptacles, ANSI/UL 498 and CSA CAN/C22.2 No. 42-99, General
Use Receptacles, Attachment Plugs, and Similar Wiring Devices.
Grade
Designations, Marketing Information and Product Features
In these standards, straight blade receptacles are
assigned four grades: general use, hospital, federal
specifications (fed. spec.), and combination hospital/fed.
spec. Each grade has its own distinct marking requirements.
The standards do not acknowledge the other receptacle
marketing designations (e.g., commercial grade or heavy duty).
These designations represent the manufacturer’s attempt to
assist in the selection process of an appropriate straight
blade receptacle based upon the intended usage and demands
that may be placed on the device. While they may be helpful to
the user, these designations generally have no impact on the
safety requirements applicable to the receptacles.
Marketing designations are different from
design features. Manufacturers also offer straight blade
receptacles with a variety of special features. These features
may include resistance to environmental conditions, tamper
resistant construction, or isolated ground. For example, an
isolated ground straight blade receptacle is offered in all
the different grades—General Use, Hospital, Fed. Spec., and
combination Hospital/Fed. Spec. The standards require
additional investigation to address compliance of these
special receptacle features.
Figure
1
Figure
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General Use
Receptacles
General use receptacles are the most common found in the
marketplace in both the United States and Canada. Receptacles
that are found to comply by UL with safety standards within
the U.S. and Canada are identified below.
General use receptacles are intended to
supply a variety of electrical loads in general use, and are
tested for this variety. For General use receptacles, matching
the plug configuration with the receptacle configuration is
the key step in determining if the receptacle can handle the
load. In this case, the receptacle has been evaluated to
ensure it can handle the load whether it is a lamp, vacuum
cleaner, heater, or other product.
Hospital Grade
Receptacles
In addition to complying with the general use requirements,
hospital grade receptacles are specially designed and are
subject to additional requirements of the standards. These
include additional grounding reliability, assembly integrity,
strength and durability.
Hospital grade receptacles are offered in
15 A and 20 A straight blade of the ANSI/NEMA WD6 5-15, 6-15,
5-20 and 6-20 configurations. They are intended for use in
accordance with the National Electrical Code, ANSI/NFPA
70, Article 517 (Health Care Facilities) in the United States
and the Canadian Electrical Code, Part 1 CAN/C22.1.02, Section
24 (Patient Care Areas) in Canada.
Hospital grade receptacles have the same
markings appearing on general use receptacles, but include
additional markings denoting their intended use. These
additional markings include the phrase "Hospital
Grade" or "Hosp. Grade" appearing on the back
of the receptacle (where visible during installation) and a
green dot located on the face, visible after installation with
a cover plate secured as intended.
UL does offer listing to a special
locking-type receptacle rated 20 A, 125 V. The identification
is very similar except it is marked "Hospital only"
with no green dot appearing on the face.
Figure
3
Figure
4
Federal
Specification General Use Receptacles
In addition to complying with the general use requirements,
fed. spec. receptacles have also been investigated for
compliance with US Federal Specification W-C-596,
"General Specification for Electrical Power
Connectors." The Federal Specification W-C-596 is a
document produced by the General Service Administration of the
U.S. Federal Government. It identifies construction features,
marking specifications and performance requirements beyond the
requirements of the safety standards, for the purpose of
durability and service life. Underwriters Laboratories is
authorized to apply the federal specification verification
mark.
The fed. spec. was created as a means to
help government procurement personnel in obtaining the correct
receptacle from suppliers. The fed. spec. details
configuration, electrical rating, type (single outlet or
duplex) and even including the color of the outlet face,
assigning a common descriptor. The receptacle industry adheres
to this identification scheme in lieu of their usual catalog
designations to facilitate government purchases.
Receptacles are identified by the federal
specification verification mark, capital letters "F"
and "S" each in a wing on either side of the UL
Listing Mark. The manufacturer may also indicate the federal
specification number "W-C-596F" or
"W-C-596G" with the federal specification part
number which consists of the appropriate specification sheet
and dash number described in the specification. These may
appear on the device or on the smallest container in which the
device is packaged.
Other wiring devices eligible for fed.
spec. rating include attachment plugs, cord connectors, (cable
outlets) receptacles and male inlets. They are offered in both
straight blade and locking- type configurations and an
electrical rating ranging from 120 to 600 volts with current
ratings up to 60 amperes and a frequency rating of 50/60
hertz.
Hospital
Grade/Fed. Spec. Receptacles
As the grade name indicates, hospital grade/fed. spec.
receptacles have been investigated for compliance with fed.
spec. hospital grade requirements. They too are identified by
the capital letters "F" and "S" flanking
the UL Listing Mark. The manufacturer may also indicate the
additional federal specification information on the device or
on the smallest container in which the device is packaged. The
phrase "Hospital Grade" or "Hosp. Grade"
will appear on the back of the receptacle (where visible
during installation) and a green dot will be present on the
face, visible after installation with a cover plate secured as
intended.
From time to time UL is asked the question
— "What’s the difference between a fed. spec. and a
combination hospital grade/fed. spec receptacle besides the
addition of the green dot and hospital grade identifier?"
Although they seem to visually appear the
same they are not. Each is investigated to a different set of
performance and construction requirements. For example, a fed.
spec. receptacle is not subjected to the abrupt plug removal
performance sequence of testing, whereas a hospital grade/fed.
spec. is subjected to this performance test sequence.
So, as a receptacle is being chosen or
approved for an application, the decision making process
should begin by identifying the appropriate grade (e.g., general
use) and features (e.g., tamper resistant) that
conform with the safety standards and codes, and suit the
particular installation. This information is different than
the manufacturer’s designations (e.g., heavy duty)
intended to meet the user’s preferences for the application.
For additional information, please visit
our web site at www.UL.com.
Chuck Kurten is the principal
engineer (PDE) for Wiring Devices & Components for
Underwriters Laboratories Inc. He is a member of both
domestic and international wiring device technical
committees, including those of UL, CSA, CANENA, NEMA,
IEC, IECEE CB CTL Task Force Expert and International
Association of Electrical Inspectors (IAEI). He holds an
AS in engineering science, B.S. in electrical
engineering and a master’s degree in business
administration (MBA). |
